Array Of Strings Research Articles

A geothermal climate change observatory: First year results from Emigrant Pass in northwest Utah

Temperature‐depth profiles, measured in boreholes, contain a temporal record of past changes in surface ground temperature and provide valuable constraints on climatic variations over the last few centuries. However, the linkage between ground temperature and meteorological variables including air temperature is imperfectly known. To understand that linkage better and to document in detail how the surface ground temperature changes propagate into the subsurface where they are later measured in temperature‐depth logs in boreholes, we have designed and installed a geothermal climate change observatory. Installed in arid northwest Utah, our Emigrant Pass Observatory (EPO) consists of an array of thermistor strings in the subsurface and a meteorological station at the borehole collar. Results from our first complete annual cycle, November 1, 1993, though October 31, 1994, are presented. Ground and air temperatures generally track each other but with important time‐varying offsets. The mean surface ground temperatures for the period are 11.3°C on the granite outcrop and 9.5°C for the partially shaded regolith site; mean air temperature at a 2‐m mast height above the ground is 8.8°C. The ground‐air temperature differences are variable on timescales from days to seasons, largely governed by level of absorbed solar radiation. Marginal precipitation (8.6 mm) and ephemeral snow cover did not significantly disturb the ground‐air temperature difference during the year monitored. Instrumental measurement of air temperature has nonrandom sampling biases that present problems for observing long term changes. The calculation of average annual air temperature at EPO decreases by 0.34 K as the sampling rate of air temperature is decreased from 60 s to every 12 hours. The attenuation and phase lag of thermal waves with depth confirm that heat conduction theory adequately describes the transient temperature field at this site, and yield in situ estimates of thermal diffusivity, a quantity needed to reconstruct surface ground temperature histories. Thermal diffusivity for the granite and regolith is 0.88 × 10−6 m2 s−1 and 0.45 × 10−6 m2 s−1, respectively. Energy flux calculations for the Emigrant Pass Observatory site suggest that a geothermal climate change observatory has the capability of detecting a century scale energy perturbation that is one part in a million of the instantaneous flux.

Effects of mismatch losses in photovoltaic arrays

Experimental and modeling results on the effects of mismatch losses in photovoltaic arrays are presented. Field tests conducted on each of the 192 modules are used to describe the variation in the properties of production run photovoltaic modules. Module specific estimates of a five-parameter module model are obtained by nonlinear regression. Mathematical models of four-module parallel string and series block photovoltaic array performance based on the five-parameter module model are developed and used to evaluate the variation in maximum output power and mismatch loss of arrays with random module orderings. Module maximum output power averaged 14% below the nameplate rating and exhibited a coefficient of variation of 2.1%. Mismatch losses were very small, never exceeding 0.53%. No differences between parallel string and series block arrays in array maximum output power were observed.

Simulations of flux dynamics in a layered three-dimensional system: 3D-2D vortex decoupling

We have simulated the diffusive dynamics of flux moving through a layered system under a constant driving force. The flux system is modelled as an array of strings, each consisting of a vortex in each plane. We allow for both flux-cutting and recombination. We investigate the effect of the interlayer coupling, and the strength and geometry of the pins on the IV characteristic of the system. We report results for the transformer geometry in which only the vortices in the top layer experience a driving force. We show that the driving force F c at which the 3D-2D transition occurs is pinning independent.

Padded string

A string is a sequence of characters. The operations such as copy and comparison on strings ar e usually performed character by character . This note presents a data type called padded string, a string type with faster operations . A padded string is a sequence of machine words . For 32-bi t machines, four characters can be operated in one machine instruction . Operations on padde d strings can then run faster than traditional strings such as char* in C language . An experimen t sorting an array of strings shows speedup 24% using padded string.

Dimer formation in monolayer antimony films deposited at room temperature on Si(100)−2 × 1

We have determined the bonding geometry of monolayer Sb films deposited at room temperature (RT), 375 and 550°C on Si(100) using transmission ion channeling. These new results reveal that the surface prepared at all three temperatures is terminated by symmetric SbSb dimers, with no evidence for three-dimensional growth or clustering at the lower temperatures. This is surprising in light of recent STM images that reveal locally ordered arrays of short dimer strings for the surface annealed at 550°C, but show a bumpy and disordered appearance for the surface annealed at 375°C.

Dimer formation in monolayer antimony films deposited at room temperature on Si(100)-2×1

We have determined the bonding geometry of monolayer Sb films deposited at room temperature (RT), 375 and 550°C on Si(100) using transmission ion channeling. These new results reveal that the surface prepared at all three temperatures is terminated by symmetric Sb-Sb dimers, with no evidence for three-dimensional growth or clustering at the lower temperatures. This is surprising in light of recent STM images that reveal locally ordered arrays of short dimer strings for the surface annealed at 550°C, but show a bumpy and disordered appearance for the surface annealed at 375°C.

Usefulness of the Karp-Miller-Rosenberg algorithm in parallel computations on strings and arrays

The Karp-Miller-Rosenberg (1972) algorithm was one of the first efficient (almost linear) sequential algorithms for finding repeated patterns and for string matching. In the area of efficient sequential computations on strings it was soon superseded by more efficient (and more sophisticated) algorithms. We show that the Karp-Miller-Rosenberg algorithm (KMR) must be considered as a basic technique in parallel computations. For many problems, variations of KMR give the (known) most efficient parallel algorithms. The representation of the set of basic factors (subarrays) of a string (array) produced by the algorithm is an extremely useful data structure in parallel algorithms on strings and arrays. This gives also a general unifying framework for a large variety of problems. We show that the following problems for strings and arrays can be solved by almost optimal parallel algorithms: pattern-matching, longest repeated factor (subarray), longest common factor (subarray), maximal symmetric factor (subarray). Also the following problems for strings can be solved within the same complexity bounds: finding squares, testing even palstars and compositions of k palindromes for k=2, 3, 4, computing Lyndon factorization and building minimal pattern-matching automata. In the model without concurrent writes the parallel time is O( log( n) 2) (with n processors) and in the model with concurrent writes the time, for most of the problems, is O( log( n)) (with n processors). For two problems related to the one-dimensional case (longest repeated factor and longest common factor) there were designed parallel algorithms using suffix trees (Apostolico et al. 1988). However, our data structure is simpler and, furthermore, for the two-dimensional case suffix trees do not work. The complexity of our algorithms does not depend on the size of the alphabet, except for the computation of pattern-matching automata.

The deep western boundary undercurrent off the Newfoundland ridge

Overflow water from the Denmark Straits first encounters water of its own density at the tip of the Grand Banks of Newfoundland at the northeastern end of the Sohm Abyssal Plain. Here the θ-S anomally of the overflow water acts as a dye enabling description of its mixing into the North Atlantic Deep Water. This mixing includes streaks at least 10 km long but less than 1 km in width as well as hemogenous structures as large as 100 km. A strong deep western boundary undercurrent meandering along isobaths to the west at 15–20 cm s −1 was observed at three current meter/thermistor string arrays. These arrays were deployed for 13 months and along with CTD and hydrographic sections form the data set.

Nonequilibrium Brownian dynamics simulations of shear thinning in concentrated colloidal suspensions

The effect of interparticle forces on shear thinning in concentrated aqueous and nonaqueous colloidal suspensions was studied using nonequilibrium Brownian dynamics. Hydrodynamic interactions among particles were neglected. Systems of 108 particles were studied at volume fractionsφ of 0.2 and 0.4. For the nonaqueous systems, shear thinning could be correlated with the gradual breakup of small flocs present because of the weak, attractive secondary minimum in the interparticle potential. At the highest shear rate forφ=0.4, the particles were organized into a hexagonally packed array of strings. For the strongly repulsive aqueous systems, the viscosity appeared to be a discontinuous function of the shear rate. Forφ=0.4, this discontinuity coincided with a transition from a disordered state to a lamellar structure for the suspension.

Ice drilling and mass balance at Pâkitsoq, Jakobshavn, central West Greenland

Hot water drilling and mass-balance measurements were made on the Inland Ice at Pakitsoq north-east of Jakobshavn. Two arrays of moderate and shallow-depth thermistor strings have been installed in the ice to map the englacial temperature from the ice margin to the equilibrium line. Water fluctuations were observed in a drill hole connecting to the ice bed. The measurements indicate a high subglacial water pressure dose to the ice overburden pressure.

A 10-bit 5-Msample/s CMOS two-step flash ADC

A 10-b, 5Msample/s, two-step flash A/D converter fabricated in a 1.6 mu m CMOS process is described. The architecture is based on a resistor string and capacitor arrays and was developed to overcome the disadvantages of the previous approaches, namely flash, pipelined, and classical two-step converters. With minimal capacitor matching requirements and comparator offset voltage cancellation, the converter is monotonic. To minimize charge-injection errors the converter is fully differential. A high-speed comparator architecture using three comparator stages was designed to provide a gain of more than 1000, and a comparison time of less than 10 ns. The total area of the converter excluding the bonding pads is 54 kmil/sup 2/. Power dissipation is 350 mW, of which 60 mW is dissipated in the resistor string.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Muffler mechanism for a piano

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Water Movements at a Mid-Central Basin Site: Time and Space Scales, Relation to Wind, and Internal Pressure Gradients

Current meter and thermistor string records made at a mid-basin site from May, 1979, through February, 1980, and during August, 1980, are used to determine the time and space scales of horizontal motion in mid lake and to relate these to the major forcing variables. Motions at frequencies larger than 0.125 cycles per hour are horizontally coherent over a few km only, whereas lower frequency motions may cohere significantly over tens of km in the stratified season. Of the four depths sampled, 10 m, 15 m, 20 m, and 21 m, highest current speeds are associated with circularly polarized clockwise rotating motion at the inertial period at 15-m depth. Surveillance cruise data show the mid central basin array to be located in a zone of relatively flat thermocline topography but suggested that internal pressure gradients might at times be large enough to influence bottom flow. Limited small-scale sampling in the vicinity of the mid-basin array reveals the existence of intense but short scale (5 km) internal pressure gradients that are undersampled by the array of thermistor strings (separated by 10 km). Multivariate statistical techniques in the frequency domain indicate that the internal pressure gradients estimated by means of the array of thermistor strings are of marginal dynamical significance (although the smaller scale gradients may in fact contribute substantially to the observed variance). A simple model of locally driven currents appropriate to a region of constant depth is proposed. This model and the statistical analyses together help to interpret the effects of wind stress and Coriolis forces. Many of the observed features of circulation, including seasonal evolution, can be related to the role of stratification in governing the vertical distribution of turbulent mixing.

An experimental test of the theory of waves in fluid-filled deformable tubes

It seems that no treatment of pulsating flow in deformable tubes is complete without a reference to the work of Womersley (1955) which for an infinitely long tube deals with the waves of axismmetric transverse motion and of longitudinal motion of the walls. This theory has so far been subjected to experimental test only for tethered tubes in which longitudinal wall motion is absent.A series of measurements of the longitudinal motion has been made on horizontal water-filled latex tubes suspended by an array of strings so that there is minimal longitudinal constraint except at the ends, which are fixed. One end of the tube is driven by oscillating flow produced by a piston; the other end is closed. Theory and experiment agree when the tube is long provided an entrance length greater than a wavelength is included. Tubes which are short enough for reflection from the closed end to be significant present a more complicated problem. It is found that in the entrance length the theory of Womersley cannot be applied. A more refined theory is required which takes into account a distributed end constraint more completely than as a simple boundary condition.Experiments on tethered tubes in which longitudinal wall motion is absent are also presented. These serve to demonstrate that the theory for such tubes agrees with measurements without any appreciable end effect and also shows that the small viscoelasticity of the latex rubber is correctly included.

A model of bacterial DNA segregation based upon helical geometry

A new mechanism to segregate daughter genomes in bacterial cells is suggested that is based upon the rules of geometry governing the helix clock (Mendelson, 1982a). The reorientation of cell surface string arrays used as a timing reference in the helix clock is capable of drawing apart the initial products of DNA replication. Physically linking the sister DNA replication origins to the ends of the initial cell surface string inserted into the cell surface at the start of a helix clock cycle, and linking the DNA terminus to a point along the length of the same string provides a means to mark the locations to which the genomes will segregate as well as the place where cell division will occur. The parallel packing of additional cell surface strings into an array which includes the string to which DNA is attached provides the necessary spatial rearrangements. The helical segregation model can account for the precise registration of cell divisions with the completion of replication forks in a multifork replication system, provides a basis for determining the relationship of sister cell sizes at division, and can also accommodate the asymmetrical divisions associated with minicell production and sporulation. Examination of the helical segregation theory under multifork DNA replication conditions moreover reveals that adjacent helical clocks are physically linked to one another although totally independent in terms of their progression through the clock cycle. A relationship between the initiation of DNA replication forks and the insertion of the first cell surface string associated with the start of a helix clock cycle is predicted by the model.

A system of strings and springs in three dimensions

A three-dimensional array of classical strings and springs oscillating in three dimensions is investigated with combined analytical-numerical tools. The strings are continuous and linear. The long time behavior of the system changes dramatically when the springs are changed from linear to non-linear. The equipartition of energy, even among the particles, is badly violated. The power spectrum is consistent with chaotic motion. The maximal Lyapunov exponent is vanishing within our approximation. The most remarkable finding is a certain pairing of time averages for the particles, which occurs for many initial conditions in the non-linear case.

Interfacing the ARIA II Automated Radioimmunoassay Analyzer with a Desktop Computer

A technique for developing an electronic interface between the Becton Dickinson ARIA II and a desktop computer is presented. The interface, consisting of both hardware and software components, was created for the BASIC language Hewlett-Packard 9845T, although the concepts are applicable to other computers. Hardware considerations include the proper pin-to-pin wiring configuration and relevant data transmission rates and formats. A transfer-timeout interrupt software routine captures the ARIA II data, and string array manipulation selectively prints test results.

The atomic-string approximation in cross-grating high-energy electron diffraction. I. Dispersion surface and Bloch waves

A new real-space method of calculating the dispersion surface and Bloch waves in cross-grating HEED is derived. Instead of using a large many-beam matrix to compute the dispersion surface, the equivalent two- dimensional band structure of allowed transverse energies of the Bloch waves is calculated from a small matrix obtained by approximating the KKR equations derived earlier [Ozorio de Almeida (1975). Acta Cryst. A31, 435-442]. For a close-packed array of atomic strings as in Au [111], transverse energy bands in excellent agreement with conventional 91 × 91 many-beam matrix calculations are obtained with only a 7 × 7 matrix. It is also shown how the calculation of the Bloch waves and their Fourier coefficients C(J)G may be further simplified by replacing the unit cell of the projected potential by its Wigner-Seitz circle. Numerical calculations, again for Au[ 111], show that the C(J)0 so obtained are still in excellent agreement with many-beam calculations but that the higher Fourier coefficients C(J)G, being more sensitive to the form of the Bloch waves in the interstitial region, are less accurate. The form of the Bloch waves is investigated and it is shown that near the zone-axis critical voltage, the nearly degenerate Bloch waves are almost entirely sp hybrids so that a 3 × 3 matrix may be used.

The Slinky as a model for transverse waves in a tenuous plasma

Transverse waves in a Slinky suspended by an array of strings share the dispersion relation for transverse electromagnetic waves in a tenuous plasma. Experimental results for the Slinky system are presented, suggesting a useful and simple laboratory exercise for an elementary physics course.

Characterizations of regular and context-free matrices

The u-v theorem for context-free languages is extended to prove an intercalation theorem for the family of context-free matrix languages. A row-wise iteration factor theorem is proved for the families of regular and context-free matrix languages. Characterizations of regular and context-free matrix languages are given in terms of vertical regular sequences and simple operations on vertical regular sequences. Closure of regular and context-free matrix languages under array nondeterministic finite state transducer mappings is established and an image theorem proved. This is used to give another characterization of regular matrix languages. Further it is shown that the family of regular matrix languages is a principal abstract family of matrices (AFM). The effect of string control and array control on these families are examined.